Autoclaves are large ovens used to bake or “heat cure” aerospace parts made out of carbon/fiber composites. Once the parts are “formed,” they are installed on holding fixtures and are rolled into the autoclaves for baking. There is also the situation of repairing composite parts that come from an airplane or from composite production lines. Before these parts are placed on the holding fixtures, a vacuum bag is placed to encompass the part to be baked. During the curing process a vacuum is pulled.
In order to monitor temperature of the curing process, thermocouple cables are placed on the parts and the thermocouple cables travel out of and under the vacuum bag. As vacuum is pulled, atmospheric pressure will press the vacuum bags against the part being cured. At curing temperatures, the part will get soft and the compression of the vacuum bag over conventional thermocouple cables will leave an indentation or mark-off, which is unacceptable.
In addition, vacuum seal integrity is required during the manufacturing process of carbon composite components for aircraft. A vacuum is necessary to rid the layered composite assembly of air pockets which cause structural weakness in the assembly, to compress the composite layers to conform to the desired shape, and to increase the fiber-to-resin ration to optimize strength of the composite. Temperature monitoring thermocouples require a vacuum seal since the thermocouple junction is in the vacuum side of the process and the temperature measuring instrumentation is necessarily on the ambient atmosphere side.
Vacuum seals around thermocouples monitoring the temperature of the composite curing process are usually made with pliable compounds or gaskets. To facilitate a successful vacuum tight seal, the gasket material conforms more easily to a flat profile thermocouple wire as opposed to the typical dumb-bell shaped wire pair profile. A need therefore exists for such a cable that reduces or eliminates the possibility of leak path through the space between the conductor and insulating material.
There are several prior art ribbon cables offered by various sources. None of the prior art ribbon cables, however, are designed with unique features, such as those to address the issues described above, for use in autoclave applications.